1. Field of the Invention
The present invention generally relates to reclosable bags, and more specifically, but not exclusively, concerns sealed, tamper evident reclosable bags.
2. Background
Various inventions have been made in the area of reclosable plastic bags with slider zippers. For example, the Herrington U.S. Pat. No. 5,007,143 shows a zipper profile which is opened and closed by a slider that is grasped by the user for opening and closing the bag. It is desirable in certain situations to provide tamper evidence to the user of the reclosable bag. The Hustad et al. U.S. Pat. No. 5,456,928 is an example of a patent disclosing a reclosable bag for use with food products which has tamper evident means incorporated therein. There are certain situations, for example, where a slider zipper reclosable bag is used to contain a product that is being marketed and it is also desirable to provide tamper evidence.
Certain types of items, such as perishable foods, need to be hermetically sealed within bags so as to prevent contamination. To ensure that contents of the bag have not been contaminated or tampered with by the bag being opened, such bags typically incorporate some sort of tamper evident feature. Tear lines on the bags, for example, have been used as one type of tamper evident indicator. At the tear line, the walls of the bag are weakened to allow for tearing of the bag, but the walls are not punctured along the tear line so as to maintain a hermetic seal. In one technique to create the hermetically sealed tear line, the tear line is thermally treated in order to weaken the material along the tear line. For instance, one technique uses a laser to heat and weaken layers of plastic sheets in the bag as the laser traverses along the tear line. As should be appreciated, through laser scoring a tamper evident tear line for hermetically sealed bags is able to be created. However, laser scoring equipment can be too expensive for some vendors. In addition, to ensure that the walls of the bag are not punctured, process control tolerances are required during laser scoring. Some bag manufacturers do not have the capability, environment, training, equipment and/or experience to be able to maintain appropriate control tolerances. Therefore, it is desirable for vendors that do not have the systems in place to produce hermetically sealed score lines to be able to produce hermetically sealed tamper evident bags with conventional equipment.